Selective prosaposin expression in Langerhans islets of the mouse pancreas

Aimi Fuyuki; Md Shahriar Hasan Sohel; Takeshi Homma; Kai Kitamura; Shigeo Takashima; Sawa Onouchi; Shouichiro Saito

doi:10.1016/j.tice.2024.102367

Selective prosaposin expression in Langerhans islets of the mouse pancreas

Tissue Cell. 2024 Mar 22:88:102367. doi: 10.1016/j.tice.2024.102367. Online ahead of print.

Authors

Aimi Fuyuki¹, Md Shahriar Hasan Sohel², Takeshi Homma², Kai Kitamura², Shigeo Takashima³, Sawa Onouchi¹, Shouichiro Saito⁴

Affiliations

¹ Laboratory of Veterinary Anatomy, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan; Laboratory of Veterinary Anatomy, Joint Graduate School of Veterinary Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
² Laboratory of Veterinary Anatomy, Joint Graduate School of Veterinary Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
³ Division of Genomics Research, Life Science Research Center, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
⁴ Laboratory of Veterinary Anatomy, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan; Laboratory of Veterinary Anatomy, Joint Graduate School of Veterinary Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan. Electronic address: saito.shouichiro.r5@f.gifu-u.ac.jp.

PMID: 38537378
DOI: 10.1016/j.tice.2024.102367

Abstract

The islets of Langerhans are clusters of endocrine cells surrounded by exocrine acinar cells in the pancreas. Prosaposin is a housekeeping protein required for normal lysosomal function, but its expression level is significantly different among tissues. Prosaposin also exists in various body fluids including serum. Intracellularly, prosaposin activates lysosomes and may support autophagy, and extracellularly, prosaposin promotes survival of neurons via G protein-coupled receptors. In this study, prosaposin and its mRNA expression were examined in endocrine cells of the islets as well as in exocrine acinar cells in the pancreas of mice by in situ hybridization and immunostaining. High expression levels of prosaposin were found in Alpha, Beta and Delta cells in the islets, whereas prosaposin mRNA expression was faint or negative and prosaposin immunoreactivity was negative in exocrine acinar cells. The high expression levels of prosaposin in endocrine cells may indicate that prosaposin plays a crucial role in crinophagy, which is a characteristic autophagy in peptide-secreting endocrine cells, and/or that prosaposin is secreted from pancreatic islets. Since prosaposin has been reported in serum, this study suggests a new possible function of the Langerhans islets.

Keywords: Autophagy; Crinophagy; Diabetes; Hormone; Prosaposin; Saposins.